Power Supply Assembly

A power supply assembly including a load supply converter system and energy saving transfer route both connected electrically to a load connection. The energy saving transfer route bypasses the load supply converter system, and includes a bypass switch system having a first bypass switch and second bypass switch connected in series. A control system of the power supply assembly is adapted to provide a system diagnostic operation including providing a diagnostic state for the bypass switch system by controlling the first bypass switch into a non-conducting state, and controlling the second bypass switch into a conducting in state, generating a diagnostic voltage in an output of the load supply converter system, and detecting a short circuit incident if an electric current flowing through the bypass switch system exceeds a predetermined short circuit threshold value.